How to set changelog-types at root level?

We're using the release-please github application and want to configure `changelog-types`. https://github.com/googleapis/release-please-action states that this can be set at the root level, but I can't find any documentation on doing this without the action.

Is it possible to have `changelog-types` set once for all packages in `release-please-config.json` ?

Creating a config as below triggers a schema failure warning in github with the following message:

```
[
{
"instancePath": "",
"schemaPath": "#/additionalProperties",
"keyword": "additionalProperties",
"params": {
"additionalProperty": "changelog-types"
},
"message": "must NOT have additional properties"
}
]
```

*config*
```
{
"changelog-types": [
{ "type": "feat", "section": "Features", "hidden": false },
{ "type": "fix", "section": "Bug Fixes", "hidden": false },
{ "type": "style", "section": "Styles", "hidden": false },
{"type": "chore","section": "Miscellaneous Chores", "hidden": true,"bump": false},
{ "type": "refactor", "section": "Code Refactoring", "hidden": false },
{ "type": "ci", "section": "Continuous Integration", "hidden": false }
],
"packages": {
"src/app1": {
"package-name": "app1",
"changelog-path": "CHANGELOG.md"
},
"src/app2": {
"package-name": "app2",
"changelog-path": "CHANGELOG.md"
}
},
"release-type": "simple",
"bump-minor-pre-major": true,
"separate-pull-requests": true
}
```